MathDB

P8

Part of 2017 Sharygin Geometry Olympiad

Problems(1)

Circumcenter of triangle on diagonal

Source: Sharygin Geometry Olympiad Correspondence Round 2017 P-8 (Grade-8-9)

5/1/2017
Let ADAD be the base of trapezoid ABCDABCD. It is known that the circumcenter of triangle ABCABC lies on BDBD. Prove that the circumcenter of triangle ABDABD lies on ACAC. Proposed by Ye.Bakayev
geometrycircumcircle